The light regime of the forests of the Arctic zone of the European North

The article provides an assessment of the illumination under the canopy of the forests of the Arctic zone of the European North. The level of illumination under the canopy of a stand is a strategic regulator of the processes occurring in the forest biogeocenosis, valuable information necessary for forest management, especially in a changing climate. Proper regulation of illumination is recognized as the main way to control the restoration and development of forests. To do this, it is necessary to create a database on the illumination under the canopy of various plantings and the reaction of all components of the forest to it. The illumination under the canopy of the North taiga and tundra forests has not been sufficiently studied. The research was carried out during the growing season in pine forests, spruce forests and birch forests of Pechora (Komi Republic), Arkhangelsk and Pinezhsky (Arkhangelsk region) forest districts. The illumination was measured at a height of 1.3 m around noon. The difference between the light regime of tundra forests and North taiga forests is the high permeability of the canopy. The relative illumination at an altitude of 1.3 m under the canopy of various types of tundra forests and under different types of weather exceeds the same value in the North taiga forests by 3.6-5 times. As a result, higher levels of illumination are formed here. The high permeability of the canopy in tundra forests is due to the closeness of the crowns. With a relative abundance of trees similar to the Northern taiga forests, the crown closure are almost 2 times lower. The share of solar energy transmitted under the canopy in cloudy weather is 2-16% more than in sunny weather. The influence of the type of forest on the sub-ecological illumination is ambiguous. In addition to the type of weather, it is necessary to take into account the distance from the edge of the forest. In tundra forests, the proportion of birch in the composition of the stand affects the illumination.

1. Bhadouria R., Srivastava P., Singh S., Singh R., Raghubanshi A., Singh J.S. Effects of light, nutrient and grass competition on growth of seedlings of four tropical tree species. Indian Forester, 2018, vol. 144, no. 1, pp. 54–65.

2. Canham C.D., Denslow J.S., Platt W.J., Runkle J.R., Spies T.A., White P.S. Light regimes beneath closed canopies and tree-fall gaps in temperate and tropical forests. Canadian Journal of Forest Research, 1990, vol. 20, no. 5, pp. 620631. DOI:10.1139/x90-084.

3. Daryaei A., Sohrabi H., Puerta-Piñero C. How does light avail ability affect the aboveground biomass allocation and leaf morphology of saplings in temperate mixed deciduous forests? New for., 2019, vol. 50, no. 3, pp. 409–422. DOI: 10.1007/s11056018-9666-0.

4. Feklistov P., Sobolev A., Barzut O., Neverov N. Illuminance under canopy in different types of forest in the northern taiga. Folia Forestalia Polonica. Series A – Forestry, 2021, vol. 63, no. 2, pp. 112–115. DOI: 10.2478/ffp-2021-0012.

5. Feklistov P.A., Brueva Zh.A., Verkhovtseva E.P., Bolotov I.N. Microclimate features under canopy of north taiga pine forests of different types. Forestry Bulletin, 2024, vol. 28, no. 5, pp. 30–41. DOI: 10.18698/2542-1468-2024-5-30-41. (In Russ.)

6. Feklistov P.A., Shangina N.P. Ecological factors of natural regeneration under the canopy of blueberry spruce forests. Arkhangelsk: IDSAFU, 2014. 114 p. (In Russ.)

7. Gusev I.I. Taxation of tree stands: a textbook. Arkhangelsk: AGTU, 2000. 71 p. (In Russ.)

8. Kim D.-H., Son S.-W., Suh G.-U., Jung J.-Y., Lee J.-Ch., Kim P.-G. Analysis of the Light Condition in the Forest Stand. Journal of Agriculture & Life Science, 2019, vol. 53, no. 5, pp. 75-82. DOI: 10.14397/jals.2019.53.5.75.

9. Lee R. Forest microclimatology. New York: Columbia University Press New York, 1978. 276 p.

10. Lugansky N.A., Zalesov S.V., Shavrovsky V.A. Forest science: textbook. Yekaterinburg: UGLTA, 1996. 373 p. (In Russ.)

11. Lukina N., Kuznetsova A., Tikhonova E., Smirnov V., Danilova M., Gornov A., Tebenkova D., Knyazeva S., Bakhmet O., Kryshen A., Shashkov M. Linking forest vegetation and soil carbon stock in northwestern Russia. Forests, 2020, vol. 11, no. 9, p. 979.

12. Martynenko V.P., Dmitruk L.B. Fundamentals of phytocenology. Educational and methodical complex. Vitebsk: Masherov Vitebsk State University, 2009. 108 p. (In Russ.)

13. Matsuo T., Martinez-Ramos M., Bongers F., van der Sande M.T., Poorter L. Forest structure drives changes in light heterogeneity during tropical secondary forest succession. J. Ecol., 2021, vol. 109, no. 8, pp. 2871-2884. DOI:10.1111/13652745.13680.

14. Santos V.A.H.F., Ferreira M.J. Are photosynthetic leaf traits related to the firstyear growth of tropical tree seedlings? A light-induced plasticity test in a secondary forest enrichment planting. For. Ecol. Manag., 2020, vol. 460, art. no. 117900. DOI: 10.1016/j.foreco.2020.117900.

15. Sendall K.M., Reich P.B., Lusk C.H. Size-related shifts in carbon gain and growth responses to light differ among rainforest ever greens of contrasting shade tolerance. Oecologia, 2018, vol. 187, no. 3, pp. 609–623. DOI:10.1007/s00442-018-4125-3.

16. Shapovalova A.A. Plant ecology. Saratov: Saratov Source, 2015. 80 p. (In Russ.)

17. Silva D.D., Balandier P., Boudon F., Marquier A., Godin Ch. Modeling of light transmission under heterogeneous forest canopy: an appraisal of the effect of the precision level of crown description. Annals of Forest Science, 2012, vol. 69, pp. 181– 193. DOI: 10.1007/s13595-011-0139-2.

18. Su Sh., Jin N., Wei X. Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei. Journal of Forestry Research, 2024, vol. 35, pp. 6. DOI:10.1007/s11676-023-01651-0.

19. Sukachev V.N., Zonn S.V. Methodological guidelines for the study of forest types. Moscow: USSR Academy of Sciences, 1961. 227 p. (In Russ.)

20. Valladares F., Niinemets Ü. Shade tolerance a key plant feature of complex nature and consequences. Ann. Rev. Ecol. Evol. Syst., 2008, vol. 39, pp. 237–257.

21. Veretennikov A.V. Plant physiology: textbook. Voronezh: VGLTA, 2002. 272 p. (In Russ.)

22. Zhen S.Y., van Iersel M.W., Bugbee B. Photosynthesis in sun and shade: the surprising importance of far-red photons. New Phytol., 2022, vol. 236, no. 2, pp. 538– 546. DOI: 10.1111/nph.18375.